Effects of distance on visual and audiovisual speech recognition

Face-to-face conversations in every day life are conducted over a range of distances. However, previous research provides only limited indications of the effects of distance on visual and audiovisual speech recognition. We re port an experiment which investigated effects of distance on perception of unimodal visual speech and congruent and incongruent audiovisual speech usi ng a talking face presented at distances of 1, 5, 10, 20, and 30m and audit ory, visual, congruent, and incongruent forms of the syllables /ba/, /bi/, /ga/, and /gi/. Identification of unimodal visual speech was unaffected by increasing distance to 10m, but was impaired at 20 and 30m. However, despit e these drops in unimodal visual speech identification, visual speech impro ved performance with congruent auditory speech at all distances and impaire d performance with incongruent auditory speech at distances up to 20m, indi cating that auditory speech recognition is influenced by visual speech even when encoded from distant faces. Implications of these findings for unders tanding visual and audiovisual speech recognition are discussed.